Reciprocating internal combustion engines include an engine block that defines a plurality of bores. A piston assembly is moveably disposed within and supported by each of the bores. The piston assembly includes a body having an outer surface that defines at least one groove. A split ring defining a ring gap is disposed within each of the grooves. The ring is radially expandable out of the groove and into abutting engagement with the bore.
Prior to installation into the bore, the ring is disposed in an uncompressed condition, and includes an uncompressed diameter that is larger than a diameter of the bore. In order to install the piston assembly into the bore, the ring is compressed into a compressed condition to define a diameter less than the diameter of the bore. Once installed, the ring expands radially into contact with the bore. Just prior to ring compression, an inner face of the ring at a corner facing the gap may become radially disposed outside an outer edge of the groove, which is defined as ring “pop out”.